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/*
* Copyright (c) 2016-2018 Positive Technologies, https://www.ptsecurity.com,
* Fast Positive Hash.
*
* Portions Copyright (c) 2010-2018 Leonid Yuriev <leo@yuriev.ru>,
* The 1Hippeus project (t1h).
*
* This software is provided 'as-is', without any express or implied
* warranty. In no event will the authors be held liable for any damages
* arising from the use of this software.
*
* Permission is granted to anyone to use this software for any purpose,
* including commercial applications, and to alter it and redistribute it
* freely, subject to the following restrictions:
*
* 1. The origin of this software must not be misrepresented; you must not
* claim that you wrote the original software. If you use this software
* in a product, an acknowledgement in the product documentation would be
* appreciated but is not required.
* 2. Altered source versions must be plainly marked as such, and must not be
* misrepresented as being the original software.
* 3. This notice may not be removed or altered from any source distribution.
*/
/*
* t1ha = { Fast Positive Hash, aka "Позитивный Хэш" }
* by [Positive Technologies](https://www.ptsecurity.ru)
*
* Briefly, it is a 64-bit Hash Function:
* 1. Created for 64-bit little-endian platforms, in predominantly for x86_64,
* but portable and without penalties it can run on any 64-bit CPU.
* 2. In most cases up to 15% faster than City64, xxHash, mum-hash, metro-hash
* and all others portable hash-functions (which do not use specific
* hardware tricks).
* 3. Not suitable for cryptography.
*
* The Future will Positive. Всё будет хорошо.
*
* ACKNOWLEDGEMENT:
* The t1ha was originally developed by Leonid Yuriev (Леонид Юрьев)
* for The 1Hippeus project - zerocopy messaging in the spirit of Sparta!
*/
#include "config.h"
#include "t1ha_bits.h"
/* xor-mul-xor mixer */
static __inline uint64_t mix64(uint64_t v, uint64_t p) {
v *= p;
return v ^ rot64(v, 41);
}
static __inline uint64_t final_weak_avalanche(uint64_t a, uint64_t b) {
/* LY: for performance reason on a some not high-end CPUs
* I replaced the second mux64() operation by mix64().
* Unfortunately this approach fails the "strict avalanche criteria",
* see test results at https://github.com/demerphq/smhasher. */
return mux64(rot64(a + b, 17), prime_4) + mix64(a ^ b, prime_0);
}
/* TODO: C++ template in the next version */
#define T1HA1_BODY(ENDIANNES, ALIGNESS) \
const uint64_t *v = (const uint64_t *)data; \
if (unlikely(len > 32)) { \
uint64_t c = rot64(len, 17) + seed; \
uint64_t d = len ^ rot64(seed, 17); \
const uint64_t *detent = \
(const uint64_t *)((const uint8_t *)data + len - 31); \
do { \
const uint64_t w0 = fetch64_##ENDIANNES##_##ALIGNESS(v + 0); \
const uint64_t w1 = fetch64_##ENDIANNES##_##ALIGNESS(v + 1); \
const uint64_t w2 = fetch64_##ENDIANNES##_##ALIGNESS(v + 2); \
const uint64_t w3 = fetch64_##ENDIANNES##_##ALIGNESS(v + 3); \
v += 4; \
prefetch(v); \
\
const uint64_t d02 = w0 ^ rot64(w2 + d, 17); \
const uint64_t c13 = w1 ^ rot64(w3 + c, 17); \
c += a ^ rot64(w0, 41); \
d -= b ^ rot64(w1, 31); \
a ^= prime_1 * (d02 + w3); \
b ^= prime_0 * (c13 + w2); \
} while (likely(v < detent)); \
\
a ^= prime_6 * (rot64(c, 17) + d); \
b ^= prime_5 * (c + rot64(d, 17)); \
len &= 31; \
} \
\
switch (len) { \
default: \
b += mux64(fetch64_##ENDIANNES##_##ALIGNESS(v++), prime_4); \
/* fall through */ \
case 24: \
case 23: \
case 22: \
case 21: \
case 20: \
case 19: \
case 18: \
case 17: \
a += mux64(fetch64_##ENDIANNES##_##ALIGNESS(v++), prime_3); \
/* fall through */ \
case 16: \
case 15: \
case 14: \
case 13: \
case 12: \
case 11: \
case 10: \
case 9: \
b += mux64(fetch64_##ENDIANNES##_##ALIGNESS(v++), prime_2); \
/* fall through */ \
case 8: \
case 7: \
case 6: \
case 5: \
case 4: \
case 3: \
case 2: \
case 1: \
a += mux64(tail64_##ENDIANNES##_##ALIGNESS(v, len), prime_1); \
/* fall through */ \
case 0: \
return final_weak_avalanche(a, b); \
}
uint64_t t1ha1_le(const void *data, size_t len, uint64_t seed) {
uint64_t a = seed;
uint64_t b = len;
#if T1HA_CONFIG_UNALIGNED_ACCESS == T1HA_CONFIG_UNALIGNED_ACCESS__EFFICIENT
T1HA1_BODY(le, unaligned);
#else
const bool misaligned = (((uintptr_t)data) & (ALIGNMENT_64 - 1)) != 0;
if (misaligned) {
T1HA1_BODY(le, unaligned);
} else {
T1HA1_BODY(le, aligned);
}
#endif
}
uint64_t t1ha1_be(const void *data, size_t len, uint64_t seed) {
uint64_t a = seed;
uint64_t b = len;
#if T1HA_CONFIG_UNALIGNED_ACCESS == T1HA_CONFIG_UNALIGNED_ACCESS__EFFICIENT
T1HA1_BODY(be, unaligned);
#else
const bool misaligned = (((uintptr_t)data) & (ALIGNMENT_64 - 1)) != 0;
if (misaligned) {
T1HA1_BODY(be, unaligned);
} else {
T1HA1_BODY(be, aligned);
}
#endif
}
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